Iran has released a statement saying that “The coordinates recorded on the GPS devices taken from the 10 U.S. marines (sic) confirmed their trespassing” two kilometres (1.24 miles) inside Iranian territorial waters, just off the heavily-guarded Farsi Island. The Island, about 7.8 square kilometres (three square miles) large, is situated 217 kilometres (135 miles) from Bahrain in the middle of the Persian Gulf, and is home to an Iranian Navy base.

The incident occurred at 1630 local time on the afternoon of 12 January 2016, after the two Riverine Command Boats (RCB) set sail for the U.S. Navy’s Fifth Fleet Headquarters in Bahrain from Kuwait, a trip of around 466 kilometres (290 miles) long. The Boats were to rendezvous with the U.S. Coast Guard patrol cutter Monomoy (WPB-1326) at 1700 to refuel in international waters.

U.S. Central Command released an account on Monday that “The planned transit path for the mission was down the middle of the Gulf and not through the territorial waters of any country other than Kuwait and Bahrain” and that the two Command Boats somehow “deviated” from their assigned route. Central Command Naval Headquarters received a report that the Command Boats’ crew were being questioned by Iranian military personnel just 10 minutes after the refueling was scheduled to take place. Central Command “was advised of degraded communications with the RCBs” at 1729, and eventually losing all communications with the Boats 26 minutes later.

The account further stated that “At some point one (of the two boats) had indications of a mechanical issue in a diesel engine which caused the crews to stop, and begin troubleshooting” and that “This stop occurred in Iranian territorial waters, although it’s not clear the crew was aware of their exact location”.

After losing contact with the two Riverine Command Boats, the U.S. Navy launched a Search-and-Rescue (SAR) operation to locate and recover the crew. Then, at 2115, the cruiser USS Anzio received word from Iran officials saying that the American sailors were safe in Iranian custody. At the time of the incident, U.S. Navy aircraft carrier USS Harry S. Truman was 72.4 kilometres (45 miles) southeast of Farsi Island, while the French Navy flagship carrier Charles de Gaulle was just 64.3 kilometres (40 miles) north of the Island.

This was argued by Iranian Revolutionary Guard Corps officials in their parliamentary statement that the U.S. sailors should have knowledge of their location as the “information was recorded on their GPS devices”, which were found to be in working order and that “the Guards have got hold of that information”. Should this be true, it would successfully refute the statement made by U.S. Defense Secretary Ashton Carter that a “navigational error” was the cause of the incursion. For some reason, neither the Boats’ commander nor any of the personnel on board the remaining operational Boat made an effort to tow the stricken craft to the Monomoy or dry-dock, instead of attempting to troubleshoot an engine problem with the Boat literally dead in the water.

While stationary in Iranian waters, the Command Boats were approached, boarded and seized by armed Iranian Revolutionary Guards from two small craft, joined by two more Iranian Navy vessels that kept watch nearby. U.S. Central Command said “Initial operational reports indicate there was a verbal exchange between the sailors and the Iranians but no exchange of gunfire…” and that “At gunpoint, the RCBs were escorted to a small port facility on Farsi Island where the U.S. Sailors disembarked and were detained for approximately 15 hours”.

“Passengers of the American boats, including nine men and one woman, (are being treated) with the Islamic conduct customary of the soldiers of the Guards naval forces, and they are in good health and being kept in a proper location,” an Iranian official statement confirmed this the day after the sailors were detained.

All 10 sailors were returned to U.S. Navy custody on the morning of 13 January after Tehran concluded that they entered Iranian waters unintentionally and that the act was “not a hostile passage or for espionage”. The crew of the two Riverine Command Boats were released in international waters where they were picked up by an element from the USS Harry S. Truman carrier strike group responding to the SAR operation. The nine male and one female sailors were then flown to Qatar where they were debriefed by U.S. Navy Central Command, as a fresh crew of U.S. sailors assumed the helm of the Boats. It remains to be seen if disciplinary action would be taken against the 10 crew members.

This incident comes at a delicate time for Iran and the United States after Iran recently agreed to a landmark nuclear deal with six world powers to curb its nuclear activities in return for sanctions to be lifted. A side agreement was also made for the exchange of prisoners. Tensions between the U.S. and Iran were heightened slightly after the U.S. Navy claimed that an Iran Revolutionary Guard vessel test fired rockets near the USS Harry S. Truman in the Strait of Hormuz on 26 December 2015, just 17 days prior to the American sailors’ detainment.